Test 3

Question 1

Which of the following is true about metabolism in its entirety in all organisms?
A) Metabolism breaks down the food and produces energy.
B) Metabolism uses all of an organism’s resources.
C) Metabolism consists of all the energy transformation reactions in an organism.
D) Metabolism manages the increase of entropy in an organism.

Answer 1

C) Metabolism consists of all the energy transformation reactions in an organism.

Question 2

Which of the following is an example of potential rather than kinetic energy?
A)   Water rushing in a river
B)   Light flashes emitted by a firefly
C)   A molecule of glucose
D)   A crawling beetle foraging for food

Answer 2

C) A molecule of glucose

Question 3

For living organisms, which of the following is an important consequence of the first law of thermodynamics?
A) The energy content of an organism is constant.
B) The organism ultimately must obtain all of the necessary energy for life from its environment.
C) The entropy of an organism decreases with time as the organism grows in complexity.
D) Organisms grow by converting energy into organic matter.

Answer 3

B) The organism ultimately must obtain all of the necessary energy for life from its environment.

Question 4

Which of the following statements is a logical consequence of the second law of thermodynamics?
A) If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe.
B) If there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe.
C) Every chemical reaction must increase the total entropy of the universe.
D) Energy can be transferred or transformed, but it cannot be created or destroyed.

Answer 4

C) Every chemical reaction must increase the total entropy of the universe.

Question 5

Which of the following relating to Gibbs free energy is TRUE?
A) It is energy given to a system from outside at no cost to the system.
B) It is the energy available to do work from a system at constant temperature and pressure.
C) Processes with a positive change in Gibbs free energy are always favourable.
D) Processes with a negative change in Gibbs free energy always occur rapidly.

Answer 5

B) It is the energy available to do work from a system at constant temperature and pressure.

Question 6

Which of the following statements about energy changes in living organisms is FALSE?
A) Living organisms are open systems.
B) Living systems can include reactions which create more order (decrease entropy).
C) Cells can store energy in high energy molecules.
D) At equilibrium, there is no further free energy change (so ΔG = 0); living systems must always exist at equilibrium.

Answer 6

D) At equilibrium, there is no further free energy change (so ΔG = 0); living systems must always exist at equilibrium.

Question 7

Which of the following systems involves a decrease in entropy?
Condensation reactions
Reactions that separate monomers
Depolymerisation reactions
Hydrolysis reactions

Answer 7

Condensation reactions

Question 8

Which of the following is generally a TRUE statement regarding equilibrium?
Reactions in closed systems never reach equilibrium.
Living cells and organisms are open systems that do not reach equilibrium.
A fully functioning metabolic pathway will reach equilibrium.
Options a and c are both true.

Answer 8

Living cells and organisms are open systems that do not reach equilibrium.

Question 9

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
A)   Catabolism (catabolic pathways)
B)   Metabolism
C)   Anabolism (anabolic pathways)
D)   Dehydration

Answer 9

A) Catabolism (catabolic pathways)

Question 10

Anabolic pathways ________.
A) are usually highly spontaneous chemical reactions
B) consume energy to build up polymers from monomers
C) release energy as they degrade polymers to monomers
D) consume energy to decrease the entropy of the organism and its environment

Answer 10

B) consume energy to build up polymers from monomers

Question 11

BLANK

Answer 11

BLANK

Question 12

Which of the following is most generally FALSE with respect to enzymes?
They have an active site where a substrate binds.
They undergo changes in shape when a substrate binds.
They position their substrates to ensure that they react effectively.
They raise the activation energy for the reaction they catalyse.

Answer 12

They raise the activation energy for the reaction they catalyse.

Question 13

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as \_\_\_\_\_\_\_\_.
a noncompetitive inhibitor of the enzyme
an allosteric activator of the enzyme
a cofactor necessary for enzyme activity
a coenzyme derived from a vitamin

Answer 13

a cofactor necessary for enzyme activity

Question 14

A noncompetitive inhibitor decreases the rate of an enzyme reaction by ________.
binding at the active site of the enzyme
changing the shape of the enzyme’s active site
changing the ∆G of the reaction by binding at the allosteric site
Select this option if TWO of the above options are TRUE.

Answer 14

changing the shape of the enzyme’s active site

Question 15

Succinate dehydrogenase catalyses the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. Based on this information, which of the following is correct?
A) Succinate dehydrogenase is the enzyme, and fumarate is the substrate.
B) Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.
C) Succinate is the substrate, and fumarate is the product.
D) Fumarate is the product, and malonic acid is a noncompetitive inhibitor.

Answer 15

C) Succinate is the substrate, and fumarate is the product.

Question 16

HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?
Vaccination.
Denaturation.
Allosteric regulation.
Competitive inhibition.

Answer 16

Competitive inhibition.

Question 17

Which of the following is an example of cooperativity?
A) A molecule binding at one unit of a tetramer, allowing faster binding at each of the other three.
B) The binding of an end product of a metabolic pathway to the first enzyme that acts in the pathway.
C) One enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway.
D) Binding of an ATP molecule along with one of the substrate molecules in an active site.
Select this option if NONE of the above options is TURE

Answer 17

A) A molecule binding at one unit of a tetramer, allowing faster binding at each of the other three.

Question 18

During a laboratory experiment, you discover that an enzyme-catalysed reaction has a ∆G of -10 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?
-20 kcal/mol.
-10 kcal/mol.
0 kcal/mol.
\+10 kcal/mol.

Answer 18

-10 kcal/mol.

Question 19

Which of the listed statements describes the results of the following reaction?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

C6H12O6 is oxidised and O2 is reduced.
C6H12O6 is reduced and O2 is oxidised.
O2 is oxidised and H2O is reduced.
O2 is reduced and CO2 is oxidised.

Answer 19

C6H12O6 is oxidised and O2 is reduced.

Question 20

The ∆G for the oxidation of glucose to CO2 and water is -686 kcal/mol and the ∆G for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.
B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
D) There is no CO2 or water produced as products of glycolysis.

Answer 20

C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.

Question 21

When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is \_\_\_\_\_\_\_\_.
A)   reduced, and energy is released
B)    reduced, and energy is consumed
C)   oxidised, and energy is consumed
D)   oxidised, and energy is released

Answer 21

B) reduced, and energy is consumed

Question 22

Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (Assume there is sufficient oxaloacetate)?
A) 1 ATP, 2 CO2, 3 NADH, and 1 FADH2
B) 3 ATP, 3 CO2, 3 NADH, and 3 FADH2
C) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2
D) 38 ATP, 6 CO2, 3 NADH, and 12 FADH2

Answer 22

C) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2

Question 23

During aerobic respiration, electrons travel downhill in which sequence?
A) Glucose → NADH//FADH2 → electron transport chain → oxygen
B) Glucose → pyruvate → ATP → oxygen
C) Glucose → ATP → electron transport chain → NADH
E) Food → glycolysis → citric acid cycle → NADH → ATP

Answer 23

A) Glucose → NADH//FADH2 → electron transport chain → oxygen